This invention relates generally to an electrophotographic printing machine, and more particularly concerns an improved stapling apparatus therein.
In an electrophotographic printing machine, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. Thereafter, the charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive surface selectively discharges the charge thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive surface corresponding to the informational areas contained within the original document being reproduced. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed by bringing a developer mix into contact therewith. Generally, the developer mix comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image in image configuration. Thereafter, the toner powder image is transferred to the copy sheet. Finally, the copy sheet is heated to permanently affix the toner particles thereto in image configuration. This general approach was originally disclosed by Carlson in U.S. Pat. No. 2,297,691 and has been further amplified and described in many related patents in the art.
Freqently, it is highly desirable to produce a plurality of sets of copies with each set of copies corresponding to a set of original documents. This is generally achieved by employing a recirculating document handling system in association with the electrophotographic printing machine. The recirculating document handling system is positioned on the platen of the printing machine and advances successive original documents onto the platen so that they may be exposed, and, subsequently reproduced. Each original document, after being exposed, is returned to the stack of original documents so that it may be re-imaged for the next successive copying cycle. In this manner, collated sets of copies are formed.
Often it is desirable to secure the copies of each set to one another forming a booklet thereof. This may be achieved by stapling the copies to each other. In high speed electrophotographic printing machines, it is highly desirable to actuate the stapling apparatus rapidly. Generally, this produces high forces and requires precise timing between successive operations. It is highly desirable to minimize the forces and distribute them so that the stapling apparatus does not produce excessive vibrations, and to minimize the length of timing between each operation, i.e. clamping the set of copy sheets, driving the staple through the set of copy sheets, and clinching the legs of the staple.
Accordingly, it is a primary object of the present invention to improve the stapling apparatus so as to minimize vibrations and optimize the operation cycle thereof.